Complexes of trialkylaluminum with mixed alkali metal cyanides



3,153,075 COMPLEXES F 'IREALKYLALUMENUM WITH MIXED ALKALI METAL CYANIDES Wolf R, Kroll, Witten-Annen, Germany, assignor to Iontinental ()il Gompany, Ponca City, ()kltL, a corporation of Delaware No Drawing. Filed July 12, 1960, Ser. No. 39,20 6 Claims. (Cl. 260---448) This invention relates to complexes of trialkylaluminum compounds with mixtures of alkali metal cyanides.

Heretofore, several methods have been proposed for the production of higherolefins from lower olefins. In general, these proposed methods have involved the reaction of a trialkylaluminumcompound with a lower olefin,

specifically, ethylene to form the so-called growth product. After forming the growth product, it is heated in the presence of an additional quantity of ethylene and a finely divided metal catalyst, such as finely divided nickel.

nally, the higher olefin is recovered from the reaction mass by distillation. The former reaction may be illustrated equationwise as follows: i

CH -CHa (CHg-CHzMCHrCHa wherein x, y, and z represent integers ranging from 0-14 (average 37) and x+y'+z-=n.

The foregoing reaction may be carried out by passing ethylene through triethylaluminum, preferably in the presence of a diluent under a Wide variety of reaction conditions, e.g., 65l50 C. and 200-5000 p.s.i.g., preferably 90-120 C. and 10003500 p.s.i.g. It is to beunderstood that, instead of employing triethylaluminum as the starting trialkylaluminum in the above reaction, other low molecular weight alkyl (C -C aluminum compounds such as tripropylaluminum, tributylaluminum, triisobutylaluminum, diethylaluminum hydride, ethylaluminum dihydride, etc., may be employed; and in lieu of ethylene, other low molecular weight aliphatic mono-l-olefins, such as propylene and the like may be substituted. Generally, C -C olefins are preferred asthe growth hydrocarbon compound.

The higher olefins are produced'by heating growth product, usually at a temperature from about 50 to about 150 C. for l to 30 minutes in the presence of an additional quantity of ethylene and a catalyst, which process is known as the ,displacement reaction. The displacement reactions can. be illustrated equationwise as follows:

wherein C 115, C4Hg, Cell I13, etc.

It has been suggested that the alpha-olefins and the triethylaluminum produced in the displacement reaction can be recovered by fractional distillation. It has been suggested further that, after the separation of the triethylaluminum and the alpha-olefins, the triethylaluminum can be returned to the growth reaction and the alpha-olefins to storage. The actual process, however, is not as simple as Equation 2 indicates. This is true, because the triethylaluminum and the alpha-olefins conta ned in the displacement products tend to undergo a reverse displacement reaction; and for that reason Equation 2 is written as a reversible reaction. Furthermore, under the-conditions present, there is a tendency for the alpha-olefins to isomerize at atmospheric pressure. Investigations have demonstrated, conclusively, that the reverse displacement reaction and the tendency of the alpha-olefins to isomerize are both accelerated by the catalyst employed in the initial reaction.

United States Patent 3,153,075 Patented Oct. 13, 1964 In addition-tothe process difliculties outlined above, considerable difficultyis encountered in the separation of the different reaction or displacement components from each other by distillation. It has been found that, when triethylaluminum is reacted with ethylene and the resulting growth product is subjected to the displacement reaction, the reaction product will comprise in addition to the solvent the following components listed in order of ascend- 7 ing boiling points; to

Ethylene I Tetradecene-l Butene-l Hexadecene-l Hexene-l Octadecene-l Octene-l Eicosene-l Decene-l Higher olefins; unre- Dodecene-l acted A1R Aluminum triethyl As a specific example, it is impractical to separate triethylaluminum from dodecene-l by ordinary methods of fractional distillation.

It is an object of this invention to provide novel compositions of matter for use in the separation of alphaolefins from other products of the. displacement reaction. Other objects and advantages of the invention will be apparent as the description proceeds.

To the accomplishment of the foregoing and related ends, this invention comprises the features hereinafter fully described and particularly pointed out in the claims,

the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which Broadly the complexes are defined by the generic formula:

v i 7 R1 Mei Me nAlR2 CN R3 wherein Me and Me are diiierent alkali metals, x+y=='1,

21:15 to 2, and'R R and R 'are alkyl groups. The mixed-alkali metal cyanides act as eiiective poisons of the reduction catalystgthe presence of which ordinarily promotes the reverse displacement and isomerization reactions. Onlysmall amounts of mixed alkali metal cyanides are required to inhibit the reverse displacement reaction, Depending on the reducing catalyst, employed, .the quantity of mixed alkali metal cyanides usually varies from about 5 to about 200 parts by weight per part by weight of catalyst. When the mixed alkali metal cyanides are further employed to form the complexes of this invention, e.g., inthe process of separating the components of the displacement reaction, the amount of the mixed alkali metal cyanides used should be sufficient to react with all of the triethylaluminum present as in- Equation 3 or when the mixed alkali metal cyanide-triethyaluminum complex is used the amount of complex to be added is determined from Equation 4. Generally, it is preferred to use the theoretical amount as shown by the equations.

Formation of the mixed alkali metal cyanide-trialkylaluminum complexes is usually at temperatures ranging from room temperature to about 150 C. In general, any temperature can be used, since the complexes are formed equally well at room temperature, as well as at more elevated temperatures. It is necessary, of course, that the temperature be maintained below the decomposition temperature of the complex. The complexes have variable amounts of each alkali metal cyanide with the trialkylaluminum or by mixing calculated amounts of individual alkali metal cyanide-complexes. AS indicated by the gen-'.

eral formula, the quantity of each alkali metal cyanide is variable, with the total equaling one mole in the complex.

As pointed out previously, the complexes find particular application in the separation of alpha-olefins from triethylalurninum. are first complexed with triethylaluminum. The complex compounds (mixed cyanide-triethylaluminum complexes) and the alpha-olefins form separate layers, making it easy to remove the alpha-olefins by decanting or other similar means. If desired, the recovered alpha-olefins can be Washed to remove any residual triethylaluminum that may be present in the recovered upper layer. .Finally, the alpha-olefins can be subjected to fractional distillation. The complex salt can then be heated, bringing about its decomposition either to the 1.5 :1 complex or to the mixed alkali metal cyanides and the triethylaluminum. The thermal decomposition reactions can be illustrated as follows:

Ithas been found that there is a direct relationship between the temperature at -which the complex is heated to bring about its decomposition and the pressure. Specifically, if the pressure varies from 1 to 500 mm. of mercury, a suitable temperature range varies from about 100 to 200 C. Generally, ity is preferred to operate under a pressure varying from 1 to 20 mm. of mercury and a temperature varying from 120 to 180 C. As a rule, the temperature used is above the boiling point of the triethylaluminum 'atthe particular pressure employed. Operating under such conditions makes it possible to remove the triethyl aluminum as it is released from the complex causing the reaction to go to completion.

'The complexes of this invention provide a number of advantages over the individual alkali metal cyanide-complexes. By appropriately varying the amount of each alkali metal cyanide in the complex, it is possible to vary the melting points, solubilities in hydrocarbons, the decomposition temperatures, etc. In this manner, it becomes possible to tailor the complex to each particular system whereby easier separation is effected between the trialkylaluminum and the alpha-olefins. The complexes of this invention are differentiated from mixtures of individual alkali metal cyanide-complexes, since each complex has a single melting point.

In addition to the procedure hereinbefore described, higher olefins can also be prepared from lower olefins In this process, the mixed cyanides through the reaction of an aluminum compound having the formula:

AlR OR' with a lower olefin. This is accomplished by forming a growth product and displacing higher ole-fins from said growth product in the presence of additional lower olefin and a catalyst system comprising a reducing metal and an alkylaluminum compound. When utilizing the alkoxy aluminum compound, the growth reaction takes place as follows:

place of the aluminum I ing the formula:

same manner as hereinbefore described. Similarly, the 7 mixed alkali metal cyanides can be employed to complex with the trialkylalurninum, thereby aiding in the separation V and recovery of the alpha-olefin product. When the mixed alkali metal cyanides are employed to complex the trialkylaluminum, the complex may form a separate lower layer from the olefins and alkoxy aluminum compound, depending on the particular solvent in which the reac tion is carried out and also on the composition of the alkoxy compound. Various methods can be employed in recovering the alpha-olefins from the reaction product and complex mixture. For example, the olefins can be distilled untilthe boiling point of the alkoxy compound is reached, after which this compound can also be removed by distillation following which the complex can be decomposed, with recycling and reuse of 'the decomposed productsas hereinbefore set forth. When the complex forms a separate lower layer, the alkoxy aluminum compound and olefins can be separated from the complex layer by decantation, with the complex being decomposed separately and the alkoxy compound and olefins being separated by distillation. In another variation of the recovery procedure, the olefins are distilled, followed by decomposition of the complex and finally distillation of the alkoxy compound. Each of the foregoing procedures find application by the appropriate choice of the OR group to provide an alkoxy compound having the desired boiling point.

It is also within the scope ofthe invention to employ in alkoxy compounds materials havwherein R and R are defined as previously set forth.

tion and the scope thereof.

Example 1 (1) Preparation of Na K (2TEA)CN complex.

24.5 grams of NaCN (0.5 mole) 32.5 grams of KCN (0.5 mole) 2305 grams of aluminum triethyl (2.02 moles) The mixture was warmed up to 80 under stirring. On cooling, a melting point of 5254 was obtained, which was confirmed by remelting. (The melting point of'the 1:2 sodium cyanide complex is about 59, while that of the corresponding potassium cyanide complex is about 78 C.)

65 grams complex were stirred with 50 ml. of hexane at 70. After settling and cooling overnight, the top layer was decanted and analyzed: 0.12 percent Al. This procedure was repeated with the same complex; an aluminum .value of 0.11 percent Was obtained.

66 grams complex were stirred with 50 ml. dodecene-l at 80. After settling and cooling overnight, the top layer was decanted and analyzed: 0.72 percent Al. This procedure was repeated and gave an Al-value of 0.64 percent Al. (For comparison, the corresponding value obtained with the NaCN 2TEA complex was 0.86 percent Al.)

Example 2 In 1.5 hours, 60 grams 1:2 complex of Example 1 were decomposed to the 1:15 complex at a bath temperature of 160-200 at 4.5 mm. About grams of distillate were obtained which were practically pure TEA, while the residue (50 grams) was a clear liquid at higher temperatures.

While particular embodiments of my invention have The complex compounds of the mixed alkalimetal cyanides and trialkylaluminum provide a number of advantages in the process of this invention. Under the conditions of the process, the complexes are liquid and thus are more easily handled than the alkali metal cyanides which are solids. i

The invention having thus been described, what is claimed and desired to be secured by Letters Patent is:

1. As a new composition of matter, a complex compound of mixed sodium and potassium cyanides and triethylaluminum having the formula:

2. As a new composition of matter, a complex compound of mixed sodium and potassium cyanides and triethylaluminum having the formula:

3. The method of preparing a complex compound of mixed sodium and potassium cyanides and triethylaluminum having the formula:

winch comprises reacting equimolar amounts of sodium cyanide and potassium cyanide with aluminum triethyl, the amount of aluminum triethyl being 1.5 times the moles of alkali metal cyanide, at a temperature from room temperature to about C. for from about 1 to about 30 minutes.

4. The method of preparing a complex compound of mixed sodium and potassium cyanides and triethylaluminum having the formula:

wherein x+y=1 and 11:15 to 2.

6. The method of preparing a complex compound of mixed sodium and potassium cyanides and triethylaluminurn having the general formula Na K (nAl(C I-I )CN wherein x+y=1 and 11:15 to 2 which comprises reacting 12 moles of triethylaluminum with x moles of NaCN and y moles of KCN at a temperature from room temperature to about 150 C. for from about 1 to about 30 minutes.

References Cited in the file of this patent V v UNITED STATES PATENTS 2,844,615 Ziegler July 22, 1958 OTHER REFERENCES Article by Ziegler etal. in Justus Liebigs Annalen der Chemie, March 1960, pages 33 to 49 (pages 33 to 35 and 46 to 48 particularly relied upon). 

5. AS A NEW COMPOSITION OF MATTER, A COMPLEX COMPOUND OF MIXED SODIUM AND POTASSIUM CYANIDES AND TRIETHYLALUMINUM HAVING THE GENERAL FORMULA: 